Method of washing fabrics using polysulfonated alkylphenols

ABSTRACT

Method of washing fabrics by contacting said fabrics with an aqueous solution containing as the detergent active material from about 0.01 to 0.10 percent by weight of polysulfonated alkylphenols produced by sulfonating C16-22 monoalkylphenols of not more than 20 mol percent para alkyl content with a sulfonating agent to incorporate an average of at least 1.5 sulfonic acid groups into molecule and neutralizing the product.

United States Patent Sharman et al.

METHOD OF WASHING FABRICS USING POLYSULFONATED ALKYLPHENOLS Inventors:Samuel H. Sharman, Kensington;

Mitchell Danzik, Pinole, both of Calif.

Division of Ser. No. 34.886, May 5, 1970, Pat. No. 3,766,254.

Assignee:

US. Cl. 252/558, 252/539 Int. Cl Clld 1/22 Field of Search 252/539, 558;260/505,

References Cited UNITED STATES PATENTS 6/]940 Flett... 260/512 June 11,1974 2.205.948 6/ l 940 2.249.757 7/l94l Flett 5/ l 942 Flett 260/505[57] ABSTRACT Method of washing fabrics by contacting said fabrics withan aqueous solution containing as the detergent active material fromabout 0.01 to 0.10 percent by weight of polysulfonated alkylphenolsproduced by sulfonating Cl6-22 monoalkylphenols of not more than 20 molpercent para alkyl content with a sulfonating agent to incorporate anaverage of at least 1.5 sulfonic acid groups into molecule andneutralizing the product.

3 Claims, No Drawings Flett 260/512 METHOD OF WASHINGFABRICS USINGPOLYSULFONATED ALKYLPHENOLS C ROSS-REFERENCE TO RELATED APPLICATION Thisapplication is a division of copending application Ser. No. 34,886,filed May 5, I970 now U.S. Pat. No. 3,766,254.

BACKGROUND OF THE INVENTION However, the above-mentioned surface-activemat rials are inadequate in terms of soil removal in the absence ofphosphate builders. Increasing evidence appears to indicate thatphosphates contribute to the growth of algae in the nations streams andlakes. This algae growth poses a serious pollution threat to themaintenance of clear, good domestic water supplies.

Consequently, there has developed a need for detergent active materialswhich will function successfully in the absence of phosphate builders.Recently, certain non-phosphate building materials have been proposed asreplacements for the phosphates. Thus, materials such as the polysodiumsalts of nitrilotriacetic acid, ethylene diamine tetraacetic acid,copolymers of ethylene and maleic acid, and similar polycarboxylicmaterials have been proposed as builders. These materials, however, whenemployed with conventional detergent actives such as LAS, have, for onereason or another, not proved to be quite as effective as phosphates indetergent formulations. For example, some of the materials have provento be insufficiently biodegradable to meet present and anticipatedrequirements;

It is therefore desirable to provide compounds which are effective asdetergent active materials in the absence of phosphate builders and arealso sufficiently biodegradable that their use results in contributingnei-. ther foam producers nor phosphates to the water supply.

In addition, in the past, with heavy duty detergents, it has beenthought that to achieve good soil removal it was necessary to maintain ahigh pH in washing solutions. This concept, which began with thestrongly alkaline laundry soaps, has continued to the present dayLAS-phosphate combinations which are in widespread use in heavy dutydetergent formulations. One apparent reason for this is that thealkylbenzene sulfonate detergents are not effective in heavy dutydetergent formulations in the absence of a builder. The phosphatebuilders, for example, must be employed at a pH greater than 9 to beeffective, and even the newer builders such as sodium nitriloacetatehave a pH of about 9 in solution. The advantages to be gained with heavyduty detergents which may be employed at neutral pH are many.Deleterious effects from skin Contact are lessened. Enzyme-type soillooseners may be more easily combined in neutral solutions. Injury tofabrics is minimized. It is, therefore, desirable. to provide detergentactive materials which, in addition to the previously mentionednon-polluting characteristics, achieve their maximum detergcncy at ornear neutral pH.

The formulation of liquid heavy duty detergent compositions achievesmany desirable rcsults. They are easy to package and measure. and theiruse opens the possibility of automatic dispensing in washing machines.However, in the past it has been impracticable to formulate heavy dutydetergents in liquid form because of the insufficient solubility of theinorganic ingredients (phosphate builders, etc.) required for heavy dutyapplications and the high cost of organic substitutes for such inorganicingredients. It is therefore highly desirable to provide detergentactive materials having good water solubility and which, because oftheir excellent detergcncy without builders, can be formulated intoeffective, reasonably priced heavy duty liquid detergent formulations.

DESCRIPTION OF THE PRIOR ART US. Pat. No. 2,249,757 discloses assurface'active agents a broad class of sulfonated, branched and linear,

alkylphenols. The proposed sulfonated alkylphenols include both mono anddisulfonates. The patent claims compounds of a general formula includingalkylphenol disulfonates having from 12 to 18 carbon atoms in the alkylgroup. By way of example, the alkylphenols are prepared by reactingphenol and olefins of 14 to 15 carbon atoms obtained by caustic sodatreatment of mono- SUMMARY OF THE INVENTION It has now been found thateffective heavy-duty detergent compositions may be formulated withoutthe necessity of phosphate builders by employing as the detergent activematerials polysulfonated alkylphenols of the formula:

in which R is linear alkyl of 16 to 22 carbon atoms, X is H or awater-soluble salt-forming cation, n is atleast 1.5, and not more than25 mol percent of the sulfonated alkylphenols have R attached on thearomatic nucleus in a position para to OX.

It has been discovered that the materials which degrade the detergentperformance of the compounds in these phosphate-free formulations, arethose compounds in which the alkyl group R is substituted para to thehydroxyl group, these compounds possessing minimal detergent activity.The explanation of this phenomenon is unclear.

Thus the effective materials are primarily either ortho or meta alkylsubstituted. Preferably, the major portion of the alkyl groups will besubstituted ortho to the phenolic hydroxyl group on the ring. The metaalkyl materials are effective as phosphate-free detergents; however. thedifficulty and consequent expense of making the high meta alkylmaterials limits their use at this time in commercial formulations.

The compounds of this invention do not require the presence of a builderto achieve good detergency, and while they are effective over a broad pHrange, reach their maximum effectiveness at a pH near neutral indetergent solutions. Thus washing at a pH of 6.5 to 8.0, preferably 6.5to 7.5, will give maximum soil removal while securing the previouslymentioned advantages which inhere in the use of neutral washingsolutions. Further, the compounds may be easily compounded intoeffective liquid heavy duty formulations because of the substantialsolubility of the compounds in water and because of the lack of need foradjunctive inorganic additives such as builders.

DESCRlPTlON OF PREFERRED EMBODIMENTS The salt-forming cation X may beany of numerous materials such as alkali metal, alkaline earth metal,ammonium, or various organic cations. Examples of suitable organiccations include amino materials such as those of the followingstructure:

The alkali metal cations are preferred, and sodium ions are particularlypreferred.

The alkyl groups represented by R are, as previously noted, linear,although the presence of a random methyl radical upon the linear chain,for example. may not adversely affect the performance of the compound.Alkyl radicals representative of R include hexadecyl, heptadecyl,octadecyl, nonadecyl, eicosyl, heneicosyl, and docosyl. Heptadecyl,octadecyl, nonadecyl, eicosyl, and heneicosyl groups are preferred.

The compounds of the invention are preferably prepared by sulfonation ofa suitable alkylphenol.

The alkylphenols which are suitable as precursors for the compounds ofthis invention are prepared by meth-. ods which provide low para-contentisomer products. Such methods include thermal alkylation of phenol withan alpha olefin. thermal alkylation of phenol with an internalmonoolefm, and 'those catalytic methods which result in production of ahigh ortho-content alkylphenol. Examples of alkylation catalysts whichhave been employed to produce high ortho-content alkylphenols includevarious metal phenoxides, particularly those of aluminum and magnesium;hydrogen fluoridetreated aluminum silicate; alkyl sulfonic acids;dimethyl sulfate; benzene sulfonic acid; naphthalene sulfonic acid;transitional alumina; and gallium and indium oxides.

Employing any of these alkylation techniques, it is, as previouslynoted, important that the alkylphenol mixture must not have a paraalkylphenol content of more than 24 and preferably not more than molpercent. This may be achieved by the noted thermal or catalytic methodswith the direct product of the process having no more than theprescribed content or it may be achieved by conventional acid catalyzedalkylation followed by distillation or by separation of the componentsby various extractive techniques such as water solubilization, etc. Thisseparation may be accomplished either with the alkylphenol mixtures orwith the sulfonated products.

The alkyl groups represented by R are generally derived from eitheralcohols, olefins, or haloparaffins. The position of the attachment ofthe aromatic nucleus on the alkyl chain may be at any point. With alphaolefms the predominant point of attachment of the alkylation productwill be either at the l or 2 and principally at the 2 position of thechain. On the other hand, with an isomerized mixture of olefins orolefins derived from haloparaffins which have, in turn, been produced byhalogenation of paraffins, the position of the double bond will begenerally completely random on the chain, and thus the correspondingalkyl chain-nucleus attachment will be random.

The sulfonation of the alkylphenols to produce the compounds of thisinvention may be accomplished by any suitable method. Thus, materialswhich may be reacted with the alkylphenol include chlorosulfonic acid,oleum, or sulfuric acid. lt is only important that enough sulfonatingagent be employed to incorporate an average of at least 1.5, preferably1.6 atoms of sulfur (in the form of sulfonate groups) into eachmolecule. Each sulfonate group incorporated into these alkylphenols canbe measured as a surface active site by titration. This number isreferred to as active group incorporation (AG1). Sulfonation with oleumis preferred.

The sulfonation is usually accomplished with a ratio of at least 2 andpreferably from 4 to 10 mols of available SO from the sulfonating agentto one mol of the alkylphenol. The use of a solvent is ordinarily notrequired in carrying out the sulfonation. The alkylphenol and thesulfonating agent are simply mixed and the reaction is allowed toproceed, maintaining the temperature of the reaction mixture within thedesired limits. The time required for disulfonation will be dependentupon the reaction temperature, the sulfonating agent, the ratio ofsulfonating agent to alkylphenol, and the total quantity of reactantspresent. The reaction is usually effected at a temperature in the rangeof 0 to 150C, preferably 25 to 100C.

After sulfonation, the product may be neutralized with a water-soluble,salt-forming cationic neutralizing agent, usually a metal oxide orhydroxide, and preferably an alkaline earth metal or alkali metalhydroxide. The alkali metal hydroxides are preferred, and most preferredis sodium hydroxide.

The neutralized product, which will, contain a substantial quantity ofwater, and from 1 to 4 parts of a normally inorganic sulfate from theneutralization of excess S0 (e.g. Na- SO may be used, as is, incombination with conventional detergent additives to formulate liquidheavy duty detergents. Alternatively, water may be removed in anyquantity to complete dryness by conventional concentration techniquessuch as evaporation, distillation, drum drying, etc., to yield aconcentrated solution, a slurry, or a dry particulate solid which maythen be blended to form a heavy duty detergent.

The solid product isolated as described above may be desalted by theusual procedures as used in the alkylbenzene sulfonate art. In thismethod the solid material is mixed with about a /30 alcohol/watersolution. The insoluble inorganic sulfate is removed by filtration, andthe organic surfactant may be used as such or isolated by evaporation ofthe solvent. The liquid con centrates and slurries may be treated insimilar fashion with allowance made for the quantity of water alreadypresent. These desalting procedures give aadetergent product that isessentially free of inorganic salt.

The following examples describe the preparation of the compounds of thisinvention.

Example 1 Preparation of ortho Heptadecylphenol Disulfonate To a smallglass sulfonator (100 ml.) equipped with a mechanical stirrer was added16.8 g. (0.05 mol) of ortho heptadecylphenol (prepared by thermalalkylation of phenol with l-heptadecene). To a small dropping funnel wasadded 25.74 g. of 21.5 percent fuming sulfuric acid. The acid was addedto the alkylphenol over a period of minutes. The sulfonater was thenheated to 75C in an oil bath, and stirring was continued for a period ofminutes. The product was then neutralized to pH 7 with 2.5 N NaOl-l inan ice bath. Analysis by Hyamine titration* (*See method of House andDarragh, Anal. Chem., 26, 1492 (1954).) and dilute acid hydrolysisindicated that the product was approximately a 50/50 mixture ofheptadecylphenol disulfonate and sodium sulfate. The yield was 91percent based upon alkylphenol.

Example 2 Preparation of Heneicosylphenol Disulfonate Following thegeneral procedure of Example 1, 25.74 g. of 21.5 percent fuming sulfuricacid was reached with 19.2 g. of heneicosylphenol (prepared by anacidclay catalyzed alkylation of phenol with a mixture of heneicosenesand having a 62/38 ortho/para isomer distribution). The product wasanalyzed as in Example I and showed a 91 percent yield ofheneicosylphenol disulfate.

Following the general procedure of Example 1 a variety of materials wereprepared employing as precursors alkylphenols in which the'alkyl groupswere linear and had aromatic nucleus attachment at all positions on thealkyl group and with varying proportions of ortho and para alkylisomers. Mixtures of these materials were also prepared.

Example 3 Preparation of a Mixture of Octadecyl-, Nonadecyl-, andEicosylphenol Disulfonates A mixture of about equal amounts ofoctadecenes, nonadecenes, and eicosenes was prepared by isomerization ofthe corresponding mixture of l-isomers. This mixture was employed toalkylate the phenol. The crude alkylphenol was distilled, and thefraction having a boiling range of 444 to 472F at 5 mm/Hg was taken asthe product. Analysis of this product showed it to contain over 96percent ortho alkyl isomers.

A 360 g. portion of the distilled alkylphenol mixture was charged to an800 ml. sulfonater equipped with a thermometer, dropping funnel, refluxcondenser, and mechanical stirrer. While the material was being stronglyagitated, 514 g. of 21.5 percent fuming sulfuric acid was added throughthe dropping funnel over a period of 36 minutes while the temperaturewas maintained at from 5 to 10C. The temperature was then raised to 75Cfor minutes. The reaction was then quenched by dropping the product ontoice, cooling it to a temperature of O5C. The product was thenneutralized with 490 ml. of 50 percent NaOH. The final volume wasadjusted to 2700 ml. Analysis by the previously described method showeda percent yield of alkylphenol disulfonate.

Example 4 I Drying of Alkylphenol Disulfonate A 500 ml. portion of theproduct of Example 3 was dried in a conventional small-scale drum drierin which the drums were operated under a pressure of 30 psi of steam. inthis manner there was recovered about g. of dry particulate solid whichanalyzed 52.5 percent of the mixture alkylphenol disulfonate, 44.0percent sodium sulfate, with the balance being water.

The compounds of this invention are useful as heavy duty detergentactives. 1n the past, heavy duty detergent formulations useful forremoving soil from textiles have comprised an organic surfactant(detergent) and an inorganic phosphate builder; the phosphate beingpresent by weight, in an amount of from one to four times that of thedetergent. The compounds of the present invention are excellent soilremovers without the aid of any phosphate builder. That is, thecompounds of this invention satisfy all need for both organic surfactantand builder in the final heavy duty detergent formulation. One way thatthis may be accomplished is by preparing a mixture of the disulfonatematerials of the instant invention and an inert material, e.g., water,sodium sulfate, sodium carbonate, etc. Such mixtures may contain anyamount of disulfonate in excess of about 10 percent, preferably'lSpercent or more. One useful composition comprises from 30 to 50 percentdisulfonate and theremainder, sodium sulfate. Many other combinationsmake useful formulations and may be either liquid solutions orparticulate solids.

As heavy duty detergents. it iscontemplated that the disulfonatecompounds will be used in wash water at concentrations of about 0.01percent to about 0.10 percent. This is within the same range ofconcentrations as are employed with the present day commercialdetergents. In other words, the soil removal properties of the presentcompounds are essentially equivalent to the soil removal properties ofan equal amount of the current commercial surfactant combined with atleast an equal amount of phosphate.

Detergency of the compounds of the present invention is measured bytheir ability to remove natural sebum soil from cotton cloth. By thismethod, small swatches of cloth, soiled by rubbing over face and neck,are washed with test solutions of detergents in a miniature laboratorywasher. The quantity of soil removed by thiswashing procedure isdetermined by measuring the reflectances of the new cloth, the soiled'cloth, and the washed cloth, the results being expressed as per centsoil removal. Because of variations in degree and type of soiling, inwater and in cloth, and other unknown variables, the absolute valueofper cent soil removal is not an accurate measure of detergenteffectivenss and cannot be used to compare various deter- I gents.Therefore, the art has developed the method of using relative detergencyratings for comparing detergent effectiveness.

The relative detergency ratings are obtained by comparing andcorrelating the per cent soil removal results from solutions containingthe detergents being tested with the results from two defined standardsolutions. The two standard solutions are selected to represent adetergent system exhibiting relatively high detersive characteristicsand a system exhibiting relatively low detersive characteristics. Thesystems are assigned detergency ratings of 6.3 and 2.2 respectively.

By washing portions of each soiled cloth with the standardizedsolutions, as well as with two test solutions, the results can beaccurately correlated. The two standard solutions are identical informulation but are employed at different hardnesses.

STANDARD SOLUTION FORMULATlON Ingredient Weight "/1 Linear Alkylbenzenesulfonate (LAS) 25 Sodium triphosphate 40 Water 8 Sodium sulfate 19Sodium silicate 7 Carboxymethylcellulose 1 The standard exhibiting highdetersive characteristics (Control B) is prepared by dissolving theabove formulation (1.0 g.) in one liter of 50 ppm hard water (calculatedas 2/3 calcium carbonate and 1/3 magnesium carbonate). The low detersivestandard (Control A) contained the formulation (1.0 g.) dissolved in oneliter of 180 ppm water (same basis).

A miniature laboratory washer is so constructed that four differentsolutions can be used to wash different parts of the same swatch. Thisarrangement ensures that all four solutions are working on identicalsoil (natural facial soil). Relative detergency ratings (RDRs) arecalculated from soil removals (SRs) according to the equation:

A further refinement in the determination of relative detergency ratingswas developed. In this method, instead of employing two standardformulations, one of the formulations used in preparing the four testsolutions had a known relative detergency rating (RDR) which had beendetermined by the above formula. Relative detergency ratings of theother three formulations were then determined by comparing the percentsoil removal (SR) of these formulations with that of the knownformulation.

Table 1 presents the detergency data on a group of representativealkylphenol disulfonates, all having at least 95 percent ortho alkylattachment. For comparison, the detergency rating is given for a linearalkylbenzene sulfonate (LAS) (having from 11 to 14 carbon atom straightchain alkyl groups) both with and without a phosphate builder.

Each formulation tested comprised 25 weight percent of the test materialalong with 1 percent carboxymethylcellulose, 7 percent sodium silicate,8 percent water, and 59 percent sodium sulfate. The LAS comparisonformulations were prepared in the same way, except that in Example 2 40percent of sodium triphosphate, and only 20 percent of LAS was used. Thetest results were obtained at a pH of 7 except for the two LAS examples,which were run at a pH of 9 (without phosphate) and 10 (with phosphate).

TABLE I Effect of Molecular Weight on the Detergency of AlkylphenolDisulfonates No. Compounds Tested 50 ppm 180 ppm water water 1 Linearalkylbenzene sulfonate (LAS) 3.2 l 4 2 LAS (20%) sodium triphosphate(41)7! 5.7 3.7 3 Tetradecylphenol disulfonate 3.6 4 Hexadecylphenoldisulfonate 5.9 4.4 5 Heptadecylphenol disulfonate 5.7 4.7 6Octadecylphenol disulfonate 5.4 4.2 7 Eicosylphenul disulfonate 6.3 4.78 A blend of approximately equal amounts of octadecyl-. nonadecyl-, andeicosylphenol disulfonates 6.0 4.3 9 A blend of approximately equalamounts of hexadecyl-, heptadecyl-, octadecyl-, nonadecy1-. andeicosylphenol disulfonates 5.4 4.5

All of the above compounds were prepared by disulfonating an alkylphenolin which the aromatic nucleus is attached predominately to the numbertwo carbon of the alkyl group (end chain attachment). Essentially thesame detergency results are obtained from alkylphenol disulfonates inwhich the aromatic nucleus is not attached predominately to any onecarbon atom of the alkyl group, but is at all possible positions (randomattachment). For example, a blend of approximately equal amounts ofoctadecyl-, nonadecyl-, and eicosylphenol disulfonates having randomattachment, gave relative detergency ratings of 5.6 and 4.2 in 50 ppmand 180 ppm water, respectively (compare with test 8 above).

These examples show that the alkylphenol disulfonates having an alkylgroup chain length in excess of 14 carbon atoms are extremely efficientdetergents. The alkylphenol disulfonates of this invention remove soilas effectively as the presently commercial LAS- phosphate combinationsdo in soft water, and they are more effective in hard water.

In order to show the effect of ring positional isomers, two blends ofoctadecyl-, nonadecyl-, and eicosylphenol disulfonates having randomattachment were prepared. One blend had a para isomer content of 4percent and the other 40 percent. These two blends were then furthercombined to give a series of blends in which the para isomer contentvaried between these two values. Table II shows the detergencyeffectivenss of these various blends.

TABLE 11 Effect of para lsomer Content on the Detergency of AlkylphenolDisulfonates isomer Distribution of the Alkylphenol Disulfonate RelativeDetergency Rating The test compound comprised a blend of approximatelyequal amounts of octadecyl, nonadecyl-, and eicosylphenol disulfonateshaving random attachment.

In addition to the above, essentially percent para-octadecylphenoldisulfonates were synthesized and found to have no soil removalproperties. The detergency depressing effect of the para isomer was alsoobserved in soft water, but to a somewhat lesser degree.

The above tests show that the para-alkylphenol disulfonate has little,if any, detergency. ln mixtures with the highly effectiveortho-alkylphenol disulfonate, the para isomer compound depresses thesoil removal properties to such an extent that a 70% ortho 30% paramixture is only about as good as linear alkylbenzene sulfonate withoutphosphate (see Table l, test 1). This is unsatisfactory performance andis not acceptable for a heavy duty phosphate-free detergent.

Alkylphenol monosulfonates are known detergents and constitute the mainby-product-occurring in the preparation of alkylphenol disulfonates. Theamount of monosulfonate in the product is determined by analyzing forthe average number of surface active groups incorporated (AGl) into thealkylphenol molecule. Table lll presents the detergency of severalmixtures of monoand di-sulfonated alkylphenols prepared from a blend ofapproximately equal amounts of octadecyl-, nonadecyl-, andeicosylphenols.

TABLE lll Effect of Alkylphenol Monosulfonate Content on the Detergencyof Alkylphenol Disulfonates Relative Detergency Rating (at 0.15%concentration) These data show that the monosulfonated alkylphenol (Test17) is about equivalent to linear alkylbenzene sulfonate withoutphosphate in both hard and soft water (see Table I, test 1 Forsatisfactory phosphatefree detergent performance, it is necessary thatthe amount of mono sulfonated alkylphenol be less than 50 percent, i.e.,the AGl must be greater than 1.5.

It will be understood that the effective compositions of this inventioninclude those materials which comprise a mixture of the sulfonatedalkylphenols in which the alkyl groups vary in their carbon chain lengthbetween 16 and 24. Thus, in most instances, a single molecular weightspecies will not be as practical commercially as the mixtures, andgenerally most effective compositions will comprise mixtures wherein atleast and preferably at least percent by weight of at least two speciesof the sulfonated alkylphenols are present in which R is an alkylradical of l6, l7, l8, 19, 20, 21, or 22 carbon atoms. The preferredrange of carbon atoms will be from about 17 to 21 and most preferablyfrom about 18 to 20 carbon atoms.

The alkylphenol disulfonates may be employed in combination with otherdetergent active materials.

They are particularly effective with other dianionic materials, examplesof which include linear alkyl and alkenyl disulfates and disulfonates. Aparticularly useful class of materials for use in detergent activecombinations is that of linear 2-alkenyl or linear 2-alkyl 1,4- butanediol disulfates in which the alkenyl or alkyl groups contain from 15 to20 carbon atoms.

In employing the detergent active materials of this invention indetergent compositions, they may be formulated with additionalcompatible ingredients being optionally incorporated to enhance thedetergent properties. Such materials may include but are not limited toanticorrosion, antiredeposition, bleaching and sequestering agents, andcertain organic and inorganic alkali metal and alkaline earth metalsalts such as inorganic sulfates, carbonates, or borates. Alsononphosphate builders may be included in the composition. Examples ofthese builders are the sodium salts of nitrilotriacetic acid, ethylenediamine tetraacetic acid, and ethylene maleic acid copolymers, etc. Alsosmall quantities of phosphate builders may be included although, ofcourse, they are not necessary for effective detergency.

While the character of this invention has been described in detail withnumerous examples, this has been done by way of illustration onlyandwithout limitation of the invention. It will be apparent to thoseskilled in the art that modifications and variations of the illustrativeexamples may be made in the practice of the invention within the scopeof the following claims;

We claim:

1. In a method of washing fabric by contacting said fabric with anaqueous solution containing a detergent amount of detergent activematerial under conditions of time and temperature to effect'substantialsoil removal from the fabric, the improvement whichcomprises carryingout the washing at substantially neutral pH and in the absence ofphosphate buildersand employing as detergent active material from about0.01 percent to about 0.10 percent by weight of polysulfonatedalkylphenols of the formula in which R is linear alkyl of 16 to 22carbon atoms, X is H or an alkali metal, alkaline earth metal, ammonium,or a tertiary lower hydroxy alkyl amino cation, n is an average of 1.5to 2, and not more than 20 mol percent of the sulfonated alkylphenolshave R attached on the aromatic nucleus in a position para to OX.

2. The method of claim 1 in which R is linear alkyl of 17 to 21 carbonatoms.

3. The method of claim 1 in which n is at least 1.6.

2. The method of claim 1 in which R is linear alkyl of 17 to 21 carbonatoms.
 3. The method of claim 1 in which n is at least 1.6.